Integrated Gasification Combined Cycle (IGCC) systems are increasingly being utilized for power generation. IGCC systems use a gasification process to produce a synthesis gas (syngas) from fuel sources such as coal, heavy petroleum residues, biomass and others. The syngas is used as a fuel in gas turbines for producing electricity. IGCC systems can be advantageous in reducing carbon dioxide (CO2) emissions through mechanisms such as pre-combustion carbon capture.
IGCC power plants adopt pre-combustion systems for CO2 capture. Currently, the capture of CO2 from IGCC plants penalizes the performance of such plants, particularly in production output and efficiency. In addition, cooling of the stationary and rotating components of a gas turbine by the conventional method of extracting air from the compressor reduces turbine efficiency by, for example, reducing the Brayton cycle efficiency. This loss of efficiency is manifested due to factors such as a reduction in firing temperatures due to non-chargeable flow diluting the combustor exit temperature, a reduction in work on account of bypassing compressed air at upstream stages of the turbine, and a reduction in work potential on account of dilution effects of the coolant stream mixing in the main gas path and the associated loss of aerodynamic efficiency.